B-cell depletion of F protein-educated mice with CD22/cal does not affect antibody responses against the F protein of RSV. (A) Serum IgM and (B) serum IgG titers in B6 mice immunized on week 0 and 2 (black arrows) with F protein (F/AlPO). Control mice (PBS) were not immunized. On weeks 4 and 4 plus 5 days (white arrows) F/AlPO and PBS mice received CD22/cal or PBS alone. All mice were administered infectious RSV on week 12 (⋆). The geometric mean end point titers were determined by ELISA on serum samples of 5 mice per group. Significant differences between the groups were not observed. In A and B ▪ indicates F/AIPO/CD22/cal; •, F/AIPO; ▴, PBS/CD22/cal; X, PBS.